The Dummy Version of Density

displacement method of measuring volume

There is such a thing as a science journalist: television networks and (some) newspapers have a few. As far as we can tell here at the Antisocial Network, though, most people who consider themselves freelance journalists have only a passing familiarity with even the most basic science. Once of the key talents of true science reporters is an ability to get across scientific principles in language people who lack a science background can understand. Some have that talent, most don't: take, for example, Keren (Carrie) Perles, who showed that she didn't in "How to Determine Density" for Sciencing.com.

This is, of course, a relocated eHow.com post; and much of Perles' problem is caused by Demand Media's¹ insistence that eHow posts be 300-500 words long. Though the determination of density can be explained in about thirty words, Perles had to pad her explanation to meet that minimum word count. It's in the padding that Carrie got caught. Take a gander at her definition of density:

"Density is one of many science terms that get thrown around often--along with mass, volume, acceleration and area. Density is the concentration of matter in an object. In layman's terms, the density of an object is the amount of 'stuff' inside of it. For example, a rock has a lot more density than a sponge, because there is more material inside each bit of rock."

Ummm, no, Carrie, a rock has greater density than a sponge because a volume of rock weighs more than the same volume of sponge (or feathers, wood, plastic, wool, etc.). The density of a substance isn't the "amount of 'stuff' inside of it"; it's the mass per unit volume! Right away we knew that Perles was about to collect her second DotD award...

Carrie continues with instructions, which she apparently copied, reworded and pasted from an elementary science book. In the process, though, she made a few goofs:

• "In order to calculate an object's density, you must first calculate its mass and volume." - Those aren't calculations, Carrie, they're measurements.
• "To calculate its mass, use a triple-beam balance." - Surely we could use some other tool besides a triple-beam balance?
• "If the object is a cube, you can multiple [sic] its width, length and height together to obtain its volume." - Not familiar with the word "multiply," Carrie?
• "If the object has irregular edges, you can calculate its mass by submerging it in a graduated cylinder or similar container full of water. Then, measure the amount of water it displaces." - "Irregular edges"? WTF? Oh, and by the way, Carrie? This is the process to measure the object's volume, not "calculate its mass."...
• "If an object has holes in it, the water displacement test will not work." - Is that Perles' halfwit way of saying, "If it's hollow..."?

With misinformation and botched instructions like those, we sure as heck hope that no clueless sixth-graders ever depended on Perles to tell them how to calculate density. About the only thing she got right in the whole post is, "density = mass/volume." Talk about burying the lede: if our Dumbass of the Day had had the slightest idea what she was talking about, that would have been in the introduction. Guess they missed that in her English communications courses...

¹ Demand Media has changed its name to Leaf Group and moved most of their legacy eHow content to niche sites like Sciencing.com. The content's structure and quality have changed little, it at all.

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